1. Field of the Invention
The present invention relates to self-lubricating bearings and self-lubricating bearing assemblies, wherein the self-lubricating bearings can be manufactured easily with improved lubricating effect.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a conventional self-lubricating bearing assembly including an axle tube 90 mounted in a casing and a self-lubricating bearing 91 mounted in the axle tube 90 in a tight fitting manner. The self-lubricating bearing 91 includes an axial hole with an inner diameter R1 that is the same as an outer diameter of a shaft 92 of a rotor (not shown), thereby rotatably holding the shaft 92. The self-lubricating bearing includes relatively small pores to release lubricating oil for smoothing rotation of the shaft 92. In order to provide longer longevity for the self-lubricating bearing, in addition to an oil reservoir 93 provided in a bottom of the axle tube 90, an inner periphery defining the axial hole of the self-lubricating bearing 91 includes a groove 94 having an inner diameter R2 greater than R1 to provide an additional place for storage of lubricating oil.
FIG. 2 illustrates another conventional self-lubricating bearing assembly including a self-lubricating bearing 91xe2x80x2 that is mounted in an axle tube 90xe2x80x2. The self-lubricating bearing 91xe2x80x2 includes an axial hole for rotatably receiving a shaft 92xe2x80x2 of a rotor (not shown). An inner periphery defining the axial hole of the self-lubricating bearing 91xe2x80x2 includes a continuous groove 95xe2x80x2 for circulating the lubricating oil.
In the above-mentioned self-lubricating bearing assemblies, the self-lubricating bearings are formed by die casting, in which the groove is closed at two ends thereof, rather than in contact with end faces of the self-lubricating bearings. As a result, the grooves cannot be formed integrally with the self-lubricating bearings such that the grooves need to be machined after formation of the self-lubricating bearings. Thus, processing of the grooves is troublesome and difficult, as the self-lubricating bearing is rigid.
It is an object of the present invention to provide a self-lubricating bearing that can be manufactured easily.
It is a secondary object of the present invention to provide a self-lubricating bearing assembly that can be manufactured easily and that may receive lubricating oil for smoothing rotation of the shaft and lengthening longevity of the self-lubricating bearing.
A self-lubricating bearing includes an axle hole having a first section and a second section. The first section includes a first inner transverse length and the second section includes a second inner transverse length that is greater than the first inner transverse length. The second section is contiguous to at least one of two end faces of the self-lubricating bearing. A self-lubricating bearing assembly is constructed by a plurality of self-lubricating bearings that are stacked one another. The difference between the first inner transverse length and the second inner transverse length provides an oil-storing compartment for the lubricating oil.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.